1. Field of the Invention
The present invention relates to an automatic sheet feeding apparatus applied to a printer, a copy machine and a printing equipment having the similar function as such, and more particularly to an apparatus capable of preventing a corner of a sheet of feed paper from being turned down.
2. Description of the Prior Art
Generally, a printing equipment is furnished with an automatic sheet feeder for automatically feeding sheets of paper and a sheet supply device for preventing overlapping feed of supplied sheets of paper.
Typically, the sheet supply device is constructed such that a finger for deterring leading edges of stacked sheets of paper are fixedly installed to both leading edges of a cassette which stores by being loaded with the sheets of paper. Thus, the sheet of paper supplied by a pickup roller is deterred to be held by the finger, thereby solely feeding the sheet of paper at the top of the stacked sheets of paper. The conventional sheet supply device can slightly accomplish the purpose of supplying a single sheet of paper by the fixedly-installed finger. However, the finger is fixedly installed to be disadvantageous in that the corner of the sheet deterred by the finger is folded, i.e. dog-ear occurs. Additionally, the conventional finger structure is for simply preventing the overlapping feed by the binding force of the supplied sheet of paper and the finger. Thus, if the binding force is intensified, the sheet of paper is jammed to cause a misfeeding which inhibits the paper feeding. The misfeeding more frequently appears as the thicker sheet of paper is supplied. In order to solve this problem, a sheet supply device capable of moving the finger has been suggested, which will be described with reference to accompanying drawings as below.
As shown in FIG. 1, a shaft 203 is formed to project from one side of a cassette 100, and an orifice 201 inserted with shaft 203 is formed in the body of a finger 200. Then, a return spring 205 is flexibly installed to the rear end of the body.
According to the conventional sheet supply device constructed as above, a sheet of paper fed by a pickup roller 101 is caught at the leading edges of finger 200 to bend the upper corner thereof. Thereafter, the leading edge of the paper pushes finger 200 by the bending motion, and orifice 201 formed in the body of finger 200 is guided by shaft 203 to advance finger 200. Then, stacked sheets of paper 102 is supplied one by one, and advanced finger 200 returns to the original position by return spring 205, thereby preparing the succeeding operation.
However, the conventional sheet supply device involves drawbacks that so much resistance is imposed upon the advancing and retreating motions of finger 200 to impede a smooth operation. Also, finger 200 is formed of an iron substance identical to those of typical fingers to retain no intrinsic elasticity with the consequence of making it impossible to perfectly solve the problem of the turning down the corner of a sheet of feed paper.